Modulation system for frequency multiplier circuits



Dec. 27, 1927.

A. H. TAYLOR ET AL MODULATION SYSTEM FOR FREQUENCY MULTIPLIER CIRCUITS Filed Aug. '6, 1925 A i k a J w y m *N\ m Mm NM, 0 a H. u F m 4. w w k, w r w W NW QM Patented Dec. 27, 1 9Z7.1 "UNITED STATES I 1,654,195- PATENT OFFICE.

ALBERT H. TAYLOR AND LEO C. YOUNG, OF WASHINGTON, DISTRICT OF COLUMBIA,

ASSIGNORS T WIRED RADIO, INQ, OE NEW YORK, N. Y., A CORPORATION OI! DELA- WARE - MODULATION SYSTEM FOR FREQUENCY MULTIPLIER CIRCUITS.

Application filed August 6, 1925. SerialNo. 48,612.

Our invention relates broadly to electron tube systems and more particularly to a method of modulating an electron tube system for electrical signaling.

- One of the objects of our invention is to provide a method of modulating an electron tube system, where the frequency of alocal oscillator is multiplied and then the amphtude of the oscillations at the multi lied frequency increasedfor operation of t 1e signalin system. 1

gtill another object of our invention is to provide-a system of modulating a frequency multiplier tube circuit in an electron tube system for the production of signals wherein modulation is effected by, variation in the grid voltage of the frequency multiplying tube.

c A further object of our invention is to provide a modulation system in an electron tube circuit arrangement employing a frequency multiplier tube, where a mimmum amount of apparatusis required for effecting modulation.

A still further object ofour invention is to provide a system of" electron tubes coupled one to another where one of the tubes is employed for the production of high frequency oscillations and an adjacent tube utilized as 0 a frequency multiplier and the next adjacent tube utilized as a power amplifier where modulation becomes dependent upon the negative potential of the grid of the frequency multiplier tube, whereby small variations in the input circuit current of the frequency multiplier tube may be employed to 1 effect large fluctuations in the energy of the harmonic developed by the frequency multiplier.

Our invention relates more specifically to an electron tube system which is described more particularly in a co-pending application for Letters. Patent filed by A. Hoyt Taylor, S. N. 48,611, filed August 6., 1925. Theimprovement described herein is directed to a method of modulatin the circuit arrangement or system descri ed in the said co-pending application.

Our invention will be more clearly understood by reference to the following SPBClfiCflm tion and the accompanying drawing, which shows diagrammatically the-arrangement of the electron tubes in the signaling system and the modulation circuit in connection with the .panying drawings reference character 1 desinput circuit of the frequency multiplier 7 tube.

for connections leading to a line wire system.

'We have discovered that in a frequency multiplier tube circuit to which is coupled the output of an electron tube oscillator, that the production of harmonic frequencies and the doubling or increase of frequency is directly dependent upon the voltage im ressed across the grid and filament electro' es and --the negative biasing of .the grid. The grid circuit of the frequency multiplier tube requires'very small current variations for the production of large fluctuations in the energy of the harmonic frequency which is derived from the fundamental frequency; We, therefore, provide in the input/circuit of the frequency multiplier tube a speech frequenc transformer, the primary winding of whic is connected to a microphone or other source of variable current. B varying the negative biasing on the grid of the frequency 90 multiplier tube in accordance with speech vibrations modulation 'of the harmonic frequency may be produced. The modulated harmonic frequency is impressed u on a circuit tuned to such harmonic and t e energy then transferred to the input circuit of a' power amplifier by whic'hit is increased in amplitude and conveyed to the signaling system.

Referring more particularly to the accomignatesan electron tube arranged as an oscillator with the frequency thereof controlled by means of piezo electric crystal 2 connected in the input circuit of the oscil- 105 lator in series with booster choke 3. A neg-v ative potential is impressed upon the grid electrodel of tube 1 from the source 4 connected in the input and output circuits of each of the'tubeswith the input and'output circuits interconnected with the output circuit of one of said tubes coupled with the input circuit of a succeeding tube. The filaments 1, 10 and 11 of each of the tubes are supplied from source 12, the incandescence of each filament electrode being controllable through rheostats 14, 15 and 16. The

' oscillator tube lhas a tuned output circuit 17 comprising variable condenser 18 and inductance 19. The input circuit of the tube 10 is connected with the tuned output circuit of the tube 1. The tube 10 has a tuned circuit 20 connected'in its output circuit, the

tuned circuit consisting of variable condenser 21 and inductance 22 with the tuned circuit 20 next to the input circuit of the power'amplifier tube 11, the output circuit of which connects toany desired form of work circuit. We have illustrated the signaling system as applied to a radio telephone circuit where the output energy from the power amplifier tube 11 is impressed upon an antenna ground circuit 23-24 through coupling inductances 25 and 26. We provide plate feed condensers 27, 28 and 29 in the output circuits of the several tubes. Radio frequency choke coils 6, 30 and 31 are placed in each of the plate circuits of the several tubes, A high potential source 32 is provided which is tapped at 33 and 34 to the input circuits of tubes 10 and 11 respectively. In order to develop harmonic oscillations in the circuits interconnecting the electrodes of tube 10' of a frequency higher than the frequency of the oscillations developed in tube 1, the'grid electrode 10 is overexcited with a relatively high nega tive potential. Radio frequency choke coils 35 and 36 are disposed in each of the'biasing circuits. A coupling transformer 37 is disposed in the input circuit of tube 10 with .the primary winding 38 thereof connected to source 39 and to microphone 40. The secondary winding 41 of the modulation transffirmer 37 is connected directly in the bias ing circuit leading to thegrid electrode 10.

ere necessary we may interpose a .voice amplification system in the modulation circuit leading to the primary winding 38 of the coupling transformer.- In this manner the si aling currents may be employed to vary t e value of negative potential on the grid of the frequency multiplier tube 10 as a result of which the oscillations of increased frequency are modulated and their amplification increased by means of the power amplifier tube 11. We provide balancing eapacities 42 and 43 between the tube circuits for preventing reaction between the several tube circuits. One tube is prevented from reacting upon another and the modulation of oscillations which are multiplied in frequency through the frequency multiplier tube 10 effected.

While we have described our invention in a certain particular embodiment, we desire that it be understood that modifications may be made and that no limitations .upon the inventionare intended other than are imposed by the scope of the appended claims.

Having thus described our invention what We claim and desire to secure by Letters Patent of the United States is as follows:

1. In a signaling system the combination of a plurality of electron tubes each having input and output circuits, with the output circuit of one of said tubes interlinked with the input circuit of a succeeding tube, one of said tubes being arranged for the generation of high frequency oscillations, another of said tubes being arranged to multiply the frequency of said oscillations, and variable means connected to the input circuit of said last mentioned tube for modulating the 05-,

cillations of increased frequency thus developed.

2. In a signaling system the combination of a plurality of electron tubes each having input and output circuits, with the output circuit of one of said tubes interlinked with the input circuit of a succeeding tube, one of said tubes being arranged for the generation of high frequency oscillations, another of said tubes bein arranged to multiply the frequency of said oscillations, means for impressing a relatively high ne ative potential upon the input'circuit of saifi last mentioned tube and separate means for va sald last mentioned input circuit for modulating the oscillations of increased fre uency.

3. In a signaling system the comblnation of a plurality of electron tubes each having grid, filament and plate electrodes, input and ing the value of said negative potential 1n 'ing the value of said-negative potential on said grid electrode for modulating the oscillations of increased frequency thus developed.

4. In a signalin system the combination of a plurality of e ectron tubes each havin 0 grid, filament and plate electrodes, input and out ut circuits interconnecting said electro es, means interlinkingrthe output circuit of one of said tubes wit the inputcircuit of a succeeding tube, said first mentioned tube having means for the generation of hi h electrode of said second mentioned tube by impressing high negative bias thereon and separate means for varying the degree of overexcitation of said grid electrode in accordan'ce with signals for modulating the amplitude of oscillations of increased frequency,

5. In a signaling system the combination of a plurality of electron tubes each havin a grid, filament and plate electrodes, input an output circuits interlinking said electrodes, means interlinking the output circuit of one of said tubes with the input circuit of a succeeding tube, said first mentioned tube having means for the generation of high frequency oscillations, the next adjacent tube having means for multipl ing the frequency of the oscillations thus eveloped, and the next adjacent tube havin means for increasing the amplitude o the oscillations thus developed, a source of negative potential, circuit connections between said source and the id electrode of said second mentioned tu e, a coupling transformer disposed in said circuit connections, a modulation circuit connected with said coupling transform: er for varying the value of negative potential impressed upon the grid electrode of I said second mentioned tube for varying the amplitude of the oscillations of increased frequency thus developed.

ALBERT H. TAYLOR. LEO C. YOUNG. 

